Many successful forms of wind driven machines have been used throughout the history of man. In recent times, there has been a need to improve the efficiency of these machines, and much work has been done on ever larger and more efficient propeller designs, each utilizing the basic concept of wind as a plane passing over the blades.
The basis of the present invention is that wind can be considered as a mass, which although subject to change in form, velocity and volume, will nevertheless continue to exert a force after passing over the initial surface of a turbine blade. It can therefore, be seen that a turbine blade which allows for the decreasing efficiency of the wind mass, can utilize this secondary force to enhance the efficiency of the initial wind contact. This is accomplished in the present invention by mounting the turbine blades on a cone or the frustum of a cone in a more or less helical manner and in such a way as to allow the variations of the wind mass to pass over the turbine blades at a varying angular contact made possible by the changing helical angle of the blade. The value of this design is particularly apparent in slower moving wind.